Please show your work and submit your computer codes in order to get points. Providing correct answers without supporting details does not receive full credits. This HW covers:
For an assignment or project, you DO NOT have to submit your answers or reports using typesetting software. However, your answers must be well organized and well legible for grading. Please upload your answers in a document to the course space. Specifically, if you are not able to knit a .Rmd/.rmd file into an output file such as a .pdf, .doc, .docx or .html file that contains your codes, outputs from your codes, your interpretations on the outputs, and your answers in text (possibly with math expressions), please organize your codes, their outputs and your answers in a document in the format given below:
Problem or task or question ...
Codes ...
Outputs ...
Your interpretations ...
It is absolutely not OK to just submit your codes only. This will result in a considerable loss of points on your assignments or projects.
Please refer to the NYC flight data nycflights13 that
has been discussed in the lecture notes and whose manual can be found at
https://cran.r-project.org/web/packages/nycflights13/index.html.
We will use flights, a tibble from
nycflights13.
You are interested in looking into the average arr_delay
for 4 different month 12, 1, 7 and 8, for 3 different
carrier “UA”, “AA” and “DL”, and for distance
that are greater than 700 miles, since you suspect that colder months
and longer distances may result in longer average arrival delays. Note
that you need to extract observations from flights, and
that you are required to use dplyr for this purpose.
library(dplyr)
##
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
##
## filter, lag
## The following objects are masked from 'package:base':
##
## intersect, setdiff, setequal, union
library(nycflights13)
flights1 = flights %>% filter(month %in% c(12, 1, 7, 8), carrier %in% c("UA", "AA", "DL"), distance > 700) #extract observations
flights1 = na.omit(flights1)
flights1 = flights1 %>% mutate_at('month', as.factor)
head(flights1)
## # A tibble: 6 × 19
## year month day dep_time sched_dep_time dep_delay arr_time sched_arr_time
## <int> <fct> <int> <int> <int> <dbl> <int> <int>
## 1 2013 1 1 517 515 2 830 819
## 2 2013 1 1 533 529 4 850 830
## 3 2013 1 1 542 540 2 923 850
## 4 2013 1 1 554 600 -6 812 837
## 5 2013 1 1 554 558 -4 740 728
## 6 2013 1 1 558 600 -2 753 745
## # ℹ 11 more variables: arr_delay <dbl>, carrier <chr>, flight <int>,
## # tailnum <chr>, origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>,
## # hour <dbl>, minute <dbl>, time_hour <dttm>
The following tasks and questions are based on the extracted observations.
(1.a) For each combination of the values of carrier and
month, obtain the average arr_delay and obtain
the average distance. Plot the average
arr_delay against the average distance, use
carrier as facet; add a title “Base plot” and center the
title in the plot. This will be your base plot, say, as object
p. Show the plot p.
library(ggplot2)
summary_stats = flights1 %>% group_by(month, carrier) %>% summarise(mean_arr_delay = mean(arr_delay), mean_distance = mean(distance))
## `summarise()` has grouped output by 'month'. You can override using the
## `.groups` argument.
p = ggplot(summary_stats, aes(x = mean_distance, y = mean_arr_delay)) + geom_point() + ggtitle("Base Plot") + theme(plot.title = element_text(hjust = 0.5)) + facet_wrap(~carrier)
p
(1.b) Modify p as follows to get a plot p1:
connect the points for each carrier via one type of dashed
line; code the 3 levels of carrier as \(\alpha_1\), \(\beta_{1,2}\) and \(\gamma^{[0]}\), and display them in the
strip texts; change the legend title into “My \(\zeta\)” (this legend is induced when you
connect points for each carrier by a type of line), and put
the legend in horizontal direction at the bottom of the plot; add a
title “With math expressions” and center the title in the plot. Show the
plot p1.
carrier_map = c(expression(alpha[1]), expression(beta[1*","*2]), expression(gamma^'[0]'))
p1 = p + geom_line(aes(group = carrier, linetype = carrier)) + labs(linetype = expression(paste("My ", zeta, sep = ""))) + scale_linetype_discrete(labels = carrier_map)
p1
(1.c) Modify p1 as follows to get a plot
p2: set the font size of strip text to be 12 and rotate the
strip texts counterclockwise by 15 degrees; set the font size of the
x-axis text to be 10 and rotate the x-axis text clockwise by 30 degrees;
set the x-axis label as “\(\hat{\mu}\)
for mean arrival delay”; add a title “With front and text adjustments”
and center the title in the plot. Show the plot p2
p2 = p1 + theme(
strip.text = element_text(size = 12, angle = -15),
axis.text.x = element_text(size = 10, angle = 30, hjust = 1),
plot.title = element_text(hjust = 0.5),
axis.title.x = element_text(size = 12)
) +
labs(
x = expression(paste(hat(mu), " for mean arrival delay", sep = ""))
) +
ggtitle("With font and text adjustments")
print(p2)
This problem requires you to visualize the binary relationship
between members of a karate club as an undirected graph. Please install
the R library igraphdata, from which you can obtain the
data set karate and work on it. Create a graph for
karate. Once you obtain the graph, you will see that each
vertex is annotated by a number or letter. What do the numbers or
letters refer to? Do you see subgraphs of the graph? If so, what do
these subgraphs mean?
library(igraph)
##
## Attaching package: 'igraph'
## The following objects are masked from 'package:dplyr':
##
## as_data_frame, groups, union
## The following objects are masked from 'package:stats':
##
## decompose, spectrum
## The following object is masked from 'package:base':
##
## union
library(igraphdata)
data(karate)
?karate
plot(karate)
## This graph was created by an old(er) igraph version.
## Call upgrade_graph() on it to use with the current igraph version
## For now we convert it on the fly...
Each
node, represented by a number or letter refers to one of the 34
different members of a karate club. Additionally the letters separate
the leaders from the members of the club(s?), A is John A the president,
and H is Mr. Hi the instructor. There are two sub-graphs present marked
by a change in color, orange or blue. This refers to the two different
factions of the karate club after it was split into two separate clubs
due to the dispute between the president and the instructor.
This problem requires to to create an interactive plot using
plotly. If you want to display properly the plot in your HW
answers, you may well need to set your HW document as an html file
(instead of doc, docx or pdf file) when you compile your R codes.
Please use the mpg data set we have discussed in the
lectures. Create an interactive, scatter plot between “highway miles per
gallon” hwy (on the y-axis) and “engine displacement in
litres” displ (on the x-axis) with the color
aesthetic designated by “number of cylinders” cyl, and set
the x-axis label as “engine displacement in litres” and y-axis label as
“highway miles per gallon”. You need to check the object type for
cyl and set it correctly when creating the plot. Add the
title “# of cylinders” to the legend and adjust the vertical position of
the legend, if you can. For the last, you may look through https://plotly.com/r/legend/ for help.
library(plotly)
##
## Attaching package: 'plotly'
## The following object is masked from 'package:igraph':
##
## groups
## The following object is masked from 'package:ggplot2':
##
## last_plot
## The following object is masked from 'package:stats':
##
## filter
## The following object is masked from 'package:graphics':
##
## layout
head(mpg)
## # A tibble: 6 × 11
## manufacturer model displ year cyl trans drv cty hwy fl class
## <chr> <chr> <dbl> <int> <int> <chr> <chr> <int> <int> <chr> <chr>
## 1 audi a4 1.8 1999 4 auto(l5) f 18 29 p compa…
## 2 audi a4 1.8 1999 4 manual(m5) f 21 29 p compa…
## 3 audi a4 2 2008 4 manual(m6) f 20 31 p compa…
## 4 audi a4 2 2008 4 auto(av) f 21 30 p compa…
## 5 audi a4 2.8 1999 6 auto(l5) f 16 26 p compa…
## 6 audi a4 2.8 1999 6 manual(m5) f 18 26 p compa…
mpg = mpg %>% mutate_at('cyl', as.factor)
myplotly = plot_ly(mpg, x = ~displ, y = ~hwy, color = ~cyl, type = "scatter") %>% layout(xaxis=list(title="engine displacement in litres"), yaxis=list(title="highway miles per gallon")) %>% layout(legend=list(title=list(text="# of cylinders"))) %>% layout(legend = list(x = 100, y = 0.5))
myplotly
## No scatter mode specifed:
## Setting the mode to markers
## Read more about this attribute -> https://plotly.com/r/reference/#scatter-mode